Mitsubishi Electric fr-e700 series, Инструкция по эксплуатации

Страница: 91 / 608

Wiring Electromagnetic compatibility (EMC)
FR-E700 SC EC/ENE 3 - 55
3.9.3 Power supply harmonics
The inverter may generate power supply harmonics from its converter circuit to affect the power gen-
erator, power capacitor etc. Power supply harmonics are different from noise and leakage currents in
source, frequency band and transmission path. Take the following countermeasure suppression
techniques.
●
Measures
The harmonic current generated from the inverter to the input side differs according to various
conditions such as the wiring impedance, whether a reactor is used or not, and output frequency
and output current on the load side.
For the output frequency and output current, we understand that they should be calculated in
the conditions under the rated load at the maximum
operating frequency
.
Item Harmonics Noise
Frequency
Maximum 50 ( 3 kHz)
Several 10 kHz to 1 GHz
Environment To electric channel, power impedance To-space, distance, wiring path
Quantitative understanding Theoretical calculation possible Random occurrence, quantitative grasp-
ing difficult
Generated amount Nearly proportional to load capacity Depending on the current fluctuation
ratio (larger as switching is faster)
Affected equipment immunity Specified in standard per equipment Different depending on maker's equip-
ment specifications
Suppression example Provide reactor Increase distance
Tab. 3-26: Differences between harmonics and noises
I002049E
Fig. 3-48: Reduction of power supply harmonics
E
CAUTION:
The power factor improving capacitor and surge suppressor on the inverter output side may be
overheated or damaged by the harmonic components of the inverter output. Also, since an
excessive current flows in the inverter to activate over current protection, do not provide a
capacitor and surge suppressor on the inverter output side when the motor is driven by the
inverter. For power factor improvement, install a reactor on the inverter input side or in the DC
circuit.
Power
supply
AC reactor
(FR-BAL-B)
DC reactor
(FFR-HEL-(H)-E)
M
3~
Inverter
Do not insert power
factor improving capacitor